Laundry detergent

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A display of laundry detergent
A display of laundry detergent

Laundry detergent, or washing powder, is a substance which is a type of detergent that is added when one is washing laundry to help get the laundry cleaner. It is often colloquially called laundry soap or simply detergent or soap but because detergents lack glycerin, they are not true "soaps". It helps wash the fabric in a manner rather analogous to the way soap helps wash hands, other parts of the body, or other things cleaner than washing with water alone.[citation needed] Laundry detergent has traditionally been a powdered or granular solid, but the use of liquid laundry detergents has gradually increased over the years, and the popularity of liquid detergent now rivals that of solid detergent. Some brands also manufacture laundry soap in tablets and dissolvable packets, so as to eliminate the need to measure soap for each load of laundry. In some countries where washing clothes by hand is more popular, detergent bars are more popular. Recently, environmentally friendly detergents have enjoyed a surge in popularity.

Contents

[edit] Contents

Detergent molecules are long and the detergents can mold into different forms of matter so they can be asymmetrical: one end attracts long pieces of dirt while the other end attracts water, which is why detergent lifts dirt from wet clothes. Detergent molecules come in two forms, straight and branched - a difference that affects sudsing but not cleansing ability. The suds of the straight molecules of detergent break down quickly, while the suds of branched molecules break down slowly if at all.

A key ingredient in both solid and liquid laundry detergents is a surfactant. A surfactant is a substance which, when added to water, significantly reduces the surface tension of the water. This effect allows water to wash surfaces better. There are many different types of organic compounds which can function as surfactants. Many surfactants are thick, viscous liquids; however, some are soft, waxy or greasy solids.

Surfactants typically have somewhat longer molecules which may or may not have an electric charge. Surfactants with uncharged molecules are non-ionic surfactants. Surfactants with positively charged molecules (or ions) are cationic surfactants. Surfactants with negatively charged molecules (or ions) are anionic surfactants. Surfactants with both positively and negatively charged part in the same molecule are zwitterionic surfactants. Most brands of laundry detergent have anionic or nonionic surfactants or a mixture of the two, although cationic surfactants have been used in laundry detergents. The use of cationic and anionic surfactants together is incompatible in the same detergent. The usual content of surfactants in a typical detergent is about 8-18%.[citation needed]

In powdered or granular solid detergents, the surfactant is soaked into the solid ingredients. In liquid laundry detergents, liquid or even solid surfactant are blended into the liquid detergent. There is usually a limit on how much liquid surfactant can soak into powder or granular solids without making the solid detergent mushy. More liquid surfactant can usually be blended into a liquid detergent. The liquid detergents commonly contain at least some water to help liquefy the other additives and still have the detergent pourable. The liquid detergents may also have other solvent liquids, such as alcohol or a hydrotrope, to help blend all the additives together.

Laundry detergents may have ingredients to help control the pH of the wash water. For example, solid detergents usually contain sodium carbonate (soda ash) or sodium bicarbonate to maintain pH by neutralizing any acidic materials that may enter the wash water.

Compounds called "builders" are often used to enhance ("build") the surfactant effect. Their role is to lower the water hardness by scavenging the calcium and magnesium ions and adsorbing them or chelating them. Some form of sodium phosphate can be used here, such as trisodium orthophosphate, monosodium orthophosphate, or a form of tripolyphosphate (TPP). In some locations, phosphate is no longer used as an additive due to environmental concerns as phosphates in surface waters stimulate algal bloom.[citation needed] As alternatives, other chelating agents are used. Sodium carbonate precipitates insoluble calcium carbonate and magnesium carbonate. Organic chemicals similar to EDTA can be employed, eg. nitriloacetic acid (NTA). Borates can be used as well. Ion exchange materials are frequently used in modern formulations; the most common kind is based on synthetic zeolites, often with polycarboxylate based polyelectrolytes. The usual content of such materials in a typical detergent is about 20-45%.[citation needed]

Many detergents contain bleaches. In North American countries, sodium hypochlorite based bleach additives are more common. These work at lower temperatures and do not need activation. In Europe, peroxide-based bleaches are prevalent instead. The chemicals employed are usually sodium percarbonate and sodium perborate, or other compounds that release hydrogen peroxide. Peroxide bleaches either need higher temperature (60 °C or more) to become effective, or a suitable catalyst or activator (eg. manganese or iron complexes, or TAED) which lowers the required temperature down to 40 °C or even to room temperature. The usual content of bleaches in a typical detergent is about 15-30%.[citation needed] It is possible to overdo the bleaching; the Persil Power fiasco[citation needed] is a good example of deployment of too powerful bleaching activator.

The detergents that promise to make the laundry "whiter than white" usually contain optical brighteners, acting as phosphors that convert some ultraviolet radiation to blue light and optically offset the yellowing of the material. The usual content of optical brighteners in a typical detergent is about 0.1%.[citation needed]

Fillers are a bulk component in many detergents. Their primary role is modifying the physical properties of the material. In solid detergents, sodium sulfate or borax can be used to make the powder free-flowing. In liquid detergents alcohols are added to increase the solubility of the compounds and to lower the mixture's freezing point. Corrosion inhibitors can be added to prolong the lifetime of the washing machines; sodium silicate can be used here. Anti-foaming agents are added to lower the production of foam and to make the presence of detergents in wastewater less obvious. The usual content of fillers in a typical detergent is about 5-45%.[citation needed]

Some laundry detergents have enzymes to help in removal of biological stains (eg. grass or blood), often enzymes produced by the bacteria Bacillus subtilis and Bacillus licheniformis. The content of enzymes can reach up to 0.75%.[citation needed] These are known as biological detergents in the United Kingdom.

Some laundry detergents have fabric softeners though the technology needed to deliver softness within a detergent product is very different to the technology when applied independently. Natural products such as clay can be used as well as long change polymers. Similar ideas to how hair conditioners work by attracting fat molecules to fibres. Some brands of detergent add more ingredients to enhance the perfume and/or color of the product. The perfume is designed to smell attractive in many situations, when the product is smelled by the user, when the washing is wet and finally when the washing is dry. Advanced materials allow slow release of perfume so that consumers can continue to smell it after several days.

During the late 90's, there was a big push for developing solid tablets that would dissolve in the washing machine. This idea was done to make it easier to dose the right amount into the washing machine, and make it an easier task for consumers. Two competing technologies were developed for the European market, one a solid tablet (Unilever) and a coated tablet (Procter & Gamble). Kao Chemical of Japan also developed a powder bag that would dissolve. The tablet market became very large in Europe, though mainly within the UK, but the idea didn't take off in America or Japan. Europe continued with this type of innovation and single dose liquid tablets were launched by the two big detergent companies. This is a technology using PVA films, which dissolve in contact with water. Therefore the liquid detergent contained within the PVA capsule, has to be especially developed not to contain any available water. If a consumer touches a PVA capsule with wet hands, they can leak. They need to be stored within dry conditions. Due to the formulation restrictions of no water, all of the technologies used in other forms may not always be applicable to this form. The capsules prevent the consumer from sensing the smell of the detergent, so companies often spray small amounts of perfume within the box to keep this important experience available.

Other brands, however, are left without these additives, marketed to those who avoid these because of allergies or individual preference. There are also detergents made with vegetable-based surfactants which are popular in health food stores.

In terms of cleaning performance, typically ranking is as follows: Powders Powder Tablets (soluble) Liquids Liquid soluble packets.

[edit] Containers and sizes

Solid laundry detergent is commonly sold in cardboard boxes and plastic tubs. In many parts of the world, laundry detergent is also sold in single-use packets or sachets. This single use allows the consumer to buy the detergent they need for the day rather than having to spend a larger amount upfront. The size of the boxes can vary from small single-use boxes sold from vending machines in laundromats to large economy-size boxes. In some cases, plastic measuring scoops have been included inside the boxes. Liquid detergent is sold in plastic bottles, usually high density polyethylene or sometimes PET or other kinds. Again, various sizes are available. On large size bottles, a handle to carry the bottle is often pre-formed as part of the bottle. Above 1.5Litre it is difficult to carry a bottle without a handle. The bottle caps are often made large enough so they can be used as cups for measuring out the liquid detergent, however this can make the cap very large as the dosage can be as much as 120ml.

Dosing balls became popular during the 1990's as a way of promoting liquid detergents. The argument was that some percentage of detergent poured into the drawer of the washing machine was lost in the sump. Putting the detergent into a dosing ball that is placed directly onto the clothes, would reduce the loss to the drain. These dosing ball devices became more sophisticated including roller balls, allowing pretreatment. One of the disadvantages of the dosing ball was noise, and some of the more recent examples are coated with softer plastic material.

[edit] Environmental Impact

In the 1960s, detergent manufacturers waged an advertising battle over who had the longest lasting suds, and detergent compounds quickly appeared in the waterways. Suds began to appear in streams, rivers, lakes, and at the foot of Niagara Falls, where piles of discolored detergent foam rose eight feet high.[citation needed]

Detergents also contain phosphate additives to soften the water and thereby improve the effectiveness of the detergent molecules. It was noted that between 1940 and 1970 the amount of phosphates in city wastewater increased from 20,000 to 150,000 tons per year.[citation needed]

With the increase in phosphates, algal blooms grew splendidly on the excess phosphorus and consumed most of the oxygen in the waters, killing fish and plants.[citation needed]

As part of the switch to go green and protect the environment, by 2008, almost all liquid laundry detergent will be sold in small bottles and in concentrated form, which supposedly helps protect the by introducing less plastic into the environment[citation needed]. Some stores around the US are already carrying concentrated laundry detergent while some in the Northeast and Midwest States are only carrying the small bottles that are used for High Efficiency Washers.

[edit] Brands of laundry detergent

The name "Ultra" is not brand specific and many "Private Label" store brands use it in their product name. Stores such as Wal-Mart, Costco, Sam's Club, Smart & Final, Sears, Walgreens, Longs Drugs, Albertsons, Lucky, and Stater Bros. sell an "Ultra" detergent. They are all manufactured by the same company, Huish Detergents. CVS Pharmacy also sells a private label "Ultra" laundry detergent, but it is not manufactured by Huish Detergents.

[edit] External links

[edit] References

  • Outwater, Alice (1996). Water: A Natural History. New York, NY: Basic Books. ISBN 0-465-03780-1. 
  • Commoner, Barry (1971). The Closing Circle: Nature, Man, and Technology. New York, NY: Random House. ISBN 039442350X. 
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